In certain localities where water contains a high mineral content, sediment or lime can build up in a water heater tank. With a gas fired water heater, the gas burner is located generally in a compartment beneath the lower head, and the buildup of sediment on the lower head acts as an insulating layer to reduce the rate of heat transfer from the burner to the water in the tank. As the insulating layer increases in thickness, overheating of the lower head can result, which can, in some instances, result in rupture of the head.
To aid in preventing the buildup of sediment on the lower head of a gas fired water heater, agitator systems have been incorporated to agitate the water in the lower end of the tank. In a conventional water heater, as a faucet is opened in the water piping system, heated water will be drawn from the water heater and cold water will be introduced into the lower portion of the water heater tank. In the agitation systems as used in the past, the entry of the cold water has been employed to create the agitating action to prevent the buildup of sediment, as disclosed in U.S. Pat. Nos. 4,257,355 and 4,157,077.